Add ROS_PYTHON_VERSION to conditional context.

bloom/generators/common.py

@@ -41,6 +41,7 @@
 from bloom.logging import info
 
 from bloom.rosdistro_api import get_distribution_type
+from bloom.rosdistro_api import get_python_version
 
 from bloom.util import code
 from bloom.util import maybe_continue
@@ -128,9 +129,19 @@ def package_conditional_context(ros_distro):
     else:
         error("Bloom cannot cope with distribution_type '{0}'".format(
             distribution_type), exit=True)
+    python_version = get_python_version(ros_distro)
+    if python_version == 2:
+        ros_python_version = '2'
+    elif python_version == 3:
+        ros_python_version = '3'
+    else:
+        error("Bloom cannot cope with python_version '{0}'".format(
+            python_version), exit=True)
+
     return {
             'ROS_VERSION': ros_version,
             'ROS_DISTRO': ros_distro,
+            'ROS_PYTHON_VERSION': ros_python_version,
             }